KNIGHTIA FISH

Knightia, pronounced nye-tee-ah, is an extinct genus of clupeid bony fish that lived in the freshwater lakes and rivers of North America and Asia during the Eocene epoch, roughly 55-33 million years ago! A small schooling fish, Knightia were considered an abundant food source for larger Eocene predators, with The Green River Formation of Wyoming producing many fossil examples of larger predators found preying on them. Knightia fish belong to the same taxonomic family as herring and sardines, and as of 1987 became Wyoming’s celebrated state fossil.

KNIGHTIA FISH FOSSILIZATION

During the Eocene, very fine-grained sediments collected at the bottom of vast, ancient seas, lakes, and riverbeds. These sediments frequently engulfed the remains of various fish, reptiles, plants, insects, and other flora and fauna. Inevitably, given ideal circumstances, these animal and plant remains would turn to stone through the natural process of fossilization. During this time, the tissues and bones of the organism dissolve and are, in turn, replaced by minerals that precipitate within the organic material. This preserves the shape of the organism like that of a mold. To easily imagine this process, consider what would happen if you submerge a sponge in paint, and then remove it and allow for the paint to dry. What would you get? The answer is a hardened sponge that is colored by paint, but remaining in appearance to that of a sponge. The paint is like the minerals that precipitate over time and take over the material, leaving the look of the remains, but incorporating an entirely different chemical structure. A Knightia fish fossil is primarily composed of calcium carbonate, which is contained within a limestone matrix. A significant amount of carbon is often present within the fossil, which is indicative of left over and preserved organic remains of the fish itself.